Case Author(s): Michael Quinn, MD Farrokh Dehdashti, MD , 07/18/97 . Rating: #D2, #Q3

Diagnosis: Mesothelioma

Brief history:

65 year old male with right upper extremity pain.


Reprojection images in anterior, posterior, and lateral position.

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View second image(pt). Cross sectional images as labeled

Full history/Diagnosis is available below

Diagnosis: Mesothelioma

Full history:

65 year old male who initially presented with right upper extremity pain. Work-up revealed a mass in the peripheral right lung apex. There was associated rib destruction and pleural thickening. Biopsy was non diagnostic.




The PET images are markedly abnormal. There is increased activity in the right lung apex corresponding to the mass seen on CT in this location.The peripheral location of the mass is again noted. Of interest is the lenticular shape of the mass, with convex margins on both sides. Accumulation of activity is increased laterally compared with medially, and these is a paucity of activity centrally. There is patchy intense accumulation in the anterosuperior right pleura and posterobasal right pleura which corresponds to the regions of pleural thickening seen on CT. Moderate activity in the right anterior sulcus is present, as is a small focus in the right hilum. There is a focus of activity in the right abdomen.


Following the patient's initial CT, a needle biopsy of the right apical mass was performed. Unfortunately, this specimen was deemed non-diagnostic by pathology. The PET study clearly shows that the mass has a photopenic center. It was surmised that the biopsy was taken from this area and may have sampled the necrotic/fibrotic center of a mass. As a tissue diagnosis was necessary to determine treatment in this patient, a second biopsy was planned. The PET study was used to localize another site of biopsy in the chest to avoid another non-diagnostic study. One of the peripheral regions of activity corresponding to a pleural based lesion on CT was chosen. The subsequent biopsy of this region yielded a diagnosis of mesothelioma. Anatomical imaging modalities are limited in differentiating benign from malignant pleural abnormalities. The utility of FDG-PET in this clinical setting has been assessed in a limited fashion. Bury et al have demonstrated that FDG-PET has a sensitivity of 94% and specificity of 78% for differentiating benign from malignant pleural abnormalities. Similar results have been reported by Lowe et al (sensitivity of 94% and specificity of 67%). Malignant pleural disease typically exhibits moderate to marked FDG accumulation. A lack of FDG uptake within the pleural lesion has a high negative predictive value for absence of malignant disease. In both reports, false-positive results were seen in patients with infectious/inflammatory pleural disease. As shown in the above case, FDG-PET can be used for biospy guidance for histological confirmation.

References: 1) Knight SB, Delbeke D, Stewart JR, Sandler MP. Evaluation of pulmonary lesions with FDG-PET. Comparison of findings in patients with and without a history of prior malignancy. Chest 1996 Apr; 109(4):982-8. 2) Lowe VJ, Patz E, Harris L, Hoffman JM, Hanson M, Goodman P, Coleman RE. FDG-PET evaluation of pleural abnormalities. J Nucl Med 1994; 35:228P.

View followup image(ct). Transaxial CT slice, mid thorax

Differential Diagnosis List


ACR Codes and Keywords:

References and General Discussion of PET Tumor Imaging Studies (Anatomic field:Lung, Mediastinum, and Pleura, Category:Neoplasm, Neoplastic-like condition)

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Case number: pt014

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